The present invention relates to a communication system using a portable device provided with a communication function.
Japanese Laid-Open Patent Publication No. 2002-247656 describes an example of a portable device known in the prior art that is provided with a smart entry function. The smart entry function is one type of vehicle control performed by means of wireless communication. When a user holding a portable device, which has a preset ID code, approaches a vehicle, a controller installed in the vehicle verifies the ID code. When the controller determines that the ID code is authentic, the vehicle door is automatically unlocked. When the user, who is holding the portable device, moves away from the vehicle, the vehicle door is automatically locked.
The portable device of the prior art has a manual switch to disable the smart entry function. The manual switch is used to disable the smart entry function and reduce the power consumed by the portable device.
However, when the controller of the vehicle does not recognize that the portable device has disabled the smart entry function, the controller remains activated to support the smart entry function and thus consumes power.